Understanding the neural mechanisms of episodic memory is fundamental to memory-related psychiatric and neurological disorders, such as post traumatic stress disorder and Alzheimer's disease. Although it is clear that the neocortex and hippocampus are important for episodic memories, how sensory contents of these memories are stored is unknown. According to current theories, sensory components are stored in the neocortex, whereas the role of hippocampus is to bind the components together. However, there is no evidence for the existence of such neocortical neurons that are involved in processing the sensory components but functionally bound by HP. Our preliminary studies revealed that many cells in the primary visual cortex of freely moving rats fired at specific places of an environment, a property thought to be unique to cells in the hippocampus and its surrounding cortical areas. We hypothesize that these visual cortical neurons are involved in processing the visual components of spatial memories and influenced by hippocampal cells. Using simultaneous tetrode recordings of visual cortical and hippocampal neurons in rats performing spatial navigation tasks, this proposal will investigate the place-specific visual cortical neurons and study whether they are related to spatial learning or memory and whether they depend on the hippocampus. PUBLIC HEALTH RELEVANCE: We propose to study how sensory components of episodic memory, the type of memory for past experiences and events, are stored and recalled in the brain. The proposal will advance our understanding of how traumatic memories are retrieved in patients with post traumatic stress disorder and how stored memories are progressively lost in patients with Alzheimer's disease. Its outcomes could generate new insights into better prevention and intervention strategies of memory-related disorders.